size_gamma: SizeGamma Size Overlap Randomization Algorithm

Description Usage Arguments Value Note See Also Examples


Function to generate a random distribution of body sizes by drawing from a gamma distribution. Shape and rate parameters of the gamma are estimated from the empirical data.


size_gamma(speciesData = rnorm(50, mean = 100, sd = 1))



a vector of body sizes or other trait measurements of species. All values must be positive real numbers.


Returns a vector of simulated body sizes as the same length as speciesData.


The shape and rate parameters are estimated from the real data using the maximum likelihood estimators generated from the fitdr function in the MASS library. The flexible gamma distribution can be fit to a variety of normal, log-normal, and exponential distributions that are typical for trait data measured on a continuous non-negative scale.

See Also

fitdistr in the MASS library.


obsOverlap <- size_gamma(speciesData=rnorm(50,mean=100,sd=1))

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